(A) Field of the Invention
The invention relates to a seal arrangement as part of a duct system for supplying compressed air to a tire on a commercial vehicle wheel from a first, non-rotary member to a second member designed to rotate with the said wheel. The duct system includes an annular space between the two said members and seal means for preventing the ingress of lubricant into the said space.
(B) Description of Prior Art
A large number of different air supply or tire pressure controlling systems of this type have been proposed so far and an example is to be seen in the U.S. Pat. No. 3,705,614. A shortcoming of the known designs is however the great trouble and expense involved in the precision machining of the large-sized parts of the non-rotary member, herein referred to as the hub, and the rotary second member herein referred to as the hub housing, with the particular necessity of accurately grinding the face on which the lips of the seal rings bear. On the one hand such machining is only possible with large machine tools and on the other it is possible for the ground running faces to be damaged during later shipment.